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Fire Lt. Test 2014 > OG 6.8 Natural Gas Emergencies > Flashcards

OG 6.8 Natural Gas Emergencies Flashcards

1
Q

During a natural gas emergency, restrict vehicle and pedestrian traffic to outside a ____’ radius.

A

300 foot

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2
Q

When checking a structure with a gas monitor, what two areas are the most important areas to check?

A

Basements

Upper areas

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3
Q

You should withdraw from a structure when a gas level reaches what percentage?

A

20% or greater

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4
Q

Natural gas has a lower explosive limit of what percentage?

A

5%

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5
Q

Natural gas has a flammable range of what percentage?

A

5 to 15%

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6
Q

What items should you never bring into the natural gas hot zone?

A

Cell phones

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7
Q

What is the vapor density of natural gas?

A

0.6

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8
Q

What are the three types of gaspipe found in Portland?

A
  1. Steel
  2. Buried polyethylene
  3. Poly pipe inserted in a casing
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9
Q

Steelpipe is used for all gas pipelines of what type?

A

Transmission – pressure pipelines

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10
Q

How much pressure is the steelpipe able to maintain?

A

50 - 800 PSI

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11
Q

What is the standard pressure for steelpipe?

A

Less than 50 psi

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12
Q

What type of gas pipe is able to ground itself to the soil?

A

Steelpipe

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13
Q

What is the danger of buried polyethylene pipe or poly pipe in a casing, when it is damaged?

A

A static charge can build up causing ignition

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14
Q

What is the danger of Poly pipe to adjacent structures?

A

Little to no risk, usually localized

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15
Q

What is the most commonly used type of gaspipe found in Portland on new construction?

A

Poly pipe

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16
Q

What does Northwest natural use to upgrade existing gas service?

A

Poly pipe inserted into a casing

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17
Q

What are two situations when Northwest natural always uses steelpipe?

A

Transmission line

Soil conditions require it

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18
Q

What is the easiest way to identify poly pipe in a casing?

A
  1. A white plastic sleeve over the steelpipe where the pipe enters the soil at the meter
  2. A large metal ring placed around the pipe just below the shutoff valve
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19
Q

Is a static charge is deemed to be an issue, What might crews do to remedy the situation?

A

Dig down to the pipe greater than 10 feet away and soak pipe with water.

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20
Q

What is the primary danger when dealing with encased Poly pipe?

A

Natural gas can travel back to the casing to the main.

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21
Q

Where should you never direct the hose stream on natural gas emergencies?

A

Into the hole

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22
Q

If there is a serious natural gas leak escaping outside of the structure with no fire, and there is danger to personnel, where can you shut off the gas?

A

The valve located at the curb just on the customer side of the property line

23
Q

You should never operate any gas valve that is located where?

A

In the street

24
Q

A gas valve that is by the curb can be usually found at what three types of facilities?

A
  1. Commercial
  2. Institutional
  3. Industrial
25
Q

Is it okay to operate valves located on large complex gas meters at commercial locations?

A

Only if there is imminent life or property threat.

26
Q

When approaching a residence on the natural gas emergency what should you never use at the front door?

A

The doorbell. Knock and enter

27
Q

Is it okay to turn off the main circuit breaker to a building at a natural gas emergency?

A

no, this may cause a spark.

28
Q

When ventilating at a natural gas emergency, what type of fans should you use?

A

Electric fans with explosion proof switches

29
Q

When ventilating A structure at a natural gas emergency, Where should you start ventilating?

A

First, where the greatest concentration is, then from the top down

30
Q

If ventilation cannot be done safely inside a structure, where should you ventilate?

A

From the outside until it is safe to go inside.

31
Q

If it is necessary to extinguish a natural gas fire at a structure due to life safety issues, What should you used to extinguish the fire?

A

Dry chemical extinguisher

32
Q

If a natural gas fire is burning inside a structure, is it okay to put out the fire?

A

It is okay to put out the structure fire, Not the gas fire.

33
Q

When did Northwest natural begin placing excess flow devices on new construction?

A

January, 1999

34
Q

Where are excess flow devices located on single-family dwellings?

A

Approximately 18 inches from the distribution line towards the house

35
Q

An excess flow device will decrease gas flow by what percentage?

A

95%

36
Q

Why does the excess flow device allow 5% leakage?

A

So that natural gas can be detected.

37
Q

What can you look at to determine if there is an excess flow device on a single-family dwelling controlling natural gas?

A

Locate the metal washer on the riser, A hole shaped as a diamond will be stamped through this washer.

38
Q

On natural gas vehicles, CNG is stored in high-pressure tanks at ____ psi.

A

3000

39
Q

How quickly will a CNG fuel tank empty when there is a leak?

A

A few minutes

40
Q

In the Portland metropolitan area, CNG is primarily used in _____ vehicles.

A

Fleet

41
Q

Fleet vehicles powered with CNG can be identified by what marking?

A

Blue diamond shaped sticker with the silver border, with silver letters “CNG”

42
Q

Will Northwest natural respond to CNG fires?

A

no

43
Q

How do you extinguish a CNG fire?

A

CNG fires should not be extinguished unless jeopardizing life or property.

44
Q

Where would you find a CNG tank on fleet vehicles?

A

In the trunk

45
Q

LNG is an orderless cryogen stored at approximately____F with a vapor pressure of approximately ___ psi, and an expense ratio of approximately ____ to ____.

A

-260°F
15
620:1

46
Q

LNG is a liquid that will flow, how should you contain it?

A

Diking

47
Q

Where do LNG vapors usually travel?

A

They heat up and stay close to the ground.

48
Q

When working with LNG, what ignition sources should you eliminate?

A

Low-level ignition sources

49
Q

In the Portland Metro area, where is LNG normally used?

A

Tri-Met buses.

50
Q

What markings Will identify a vehicle using LNG?

A

Blue diamond shaped sticker with a silver border, Silver letters LNG in the middle of the sticker.

51
Q

Will Northwest natural respond to LNG emergencies?

A

Yes

52
Q

why is it a bad idea to direct water at LNG?

A

This will cause LNG vaporize at an accelerated rate.

53
Q

If necessary to extinguish a LNG fire, What should you use to extinguish the fire?

A

Dry chemical extinguisher

54
Q

What can you use to direct LNG vapors away from you?

A

Waterfog

Fire Lt. Test 2014 (102 decks)

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